Wind turbine blades with improved bond line

ABSTRACT

A wind turbine blade includes an upper shell member and a lower shell member defining an internal cavity therebetween. The shell members are joined with a bond paste along bond lines at the leading edge and trailing edge of the blade. A seal member is disposed between the upper and lower shell members at a designed width of the bond line along at least one of the trailing or leading edges. The seal member comprises a dam on each of the lower and upper shell members that overlap in a mated configuration of the shell members.

CROSS-REFERENCE TO RELATED APPLICATION

The present invention is a Continuation Application of U.S. patentapplication Ser. No. 12/823,562, filed Jun. 25, 2010.

FIELD OF THE INVENTION

The present invention relates generally to the field of wind turbines,and more particularly to turbine blades having an improved seal alongthe leading or trailing edge bonding line.

BACKGROUND OF THE INVENTION

Turbine blades are the primary elements of wind turbines for convertingwind energy into electrical energy. The blades have the cross-sectionalprofile of an airfoil such that, during operation, air flows over theblade producing a pressure difference between the sides. Consequently, alift force, which is directed from a pressure side towards a suctionside, acts on the blade. The lift force generates torque on the mainrotor shaft, which is geared to a generator for producing electricity.

The turbine blades typically consist of an upper (suction side) shelland a lower (pressure side) shell that are bonded together at bond linesalong the trailing and leading edges of the blade. The bond lines aregenerally formed by applying a suitable bonding paste or compound alongthe bond line at a minimum designed bond width between the shellmembers. The bond paste, however, tends to migrate well past thedesigned bond width and into the interior blade cavity. This excess bondpaste can add considerable weight to the blade and, thus, adverselyaffect blade efficiency and overall performance of the wind turbine.

Accordingly, the industry would benefit from an improved bond lineconfiguration that reduces the amount of excess bond paste that migratesinto the blade cavity.

BRIEF DESCRIPTION OF THE INVENTION

Aspects and advantages of the invention will be set forth in part in thefollowing description, or may be obvious from the description, or may belearned through practice of the invention.

In accordance with aspects of the invention, a wind turbine blade isprovided having an upper shell member and a lower shell member definingan internal cavity therebetween. The shell members are joined with abond paste applied in flowable form along bond lines at a leading edgeand a trailing edge of the blade. Along at least one of the trailing orleading edges, a seal member is disposed between the upper and lowershell members at a designed bond width along the bond line. The sealmember has a configuration such that excess flowable bond paste isprevented from migrating past the seal member and into the internalcavity upon mating the upper and lower shell members in assembly of theblade. In a particular embodiment, the seal members are provided alongboth of the leading and trailing edge bond lines.

The seal member may be formed from various types of material orcombinations of materials and, in a particular embodiment, isimpermeable to the flowable bond paste but air permeable so that any airtrapped in the bond line may migrate through the seal member when theupper and lower shells are pressed together.

In particular embodiments, the seal member may be one or a combinationof dam members attached to either one or both of the upper or lowershell members. The dam member may be a brush seal in a particularlyunique embodiment. The seal member may be a single dam member extendingfrom either of the upper or lower shell members towards the otherrespective shell member. Alternatively, a dam member may be provided oneach of the lower and upper shell members, with the dams intermeshing inone embodiment or overlapping in another embodiment.

The seal member in another embodiment may be a plurality of interlaceddam members that define a tortuous path for flowable bond paste.

The blade may also include a seal gap at the extreme end of the leadingor trailing edge opposite from the seal member, with the seal gapproviding an opening through which excess flowable bond paste migratesout from the bond line in assembly of the blade.

The invention also encompasses a wind turbine having one or more turbineblades configured with the unique bond line configuration describedherein.

These and other features, aspects and advantages of the presentinvention will become better understood with reference to the followingdescription and appended claims. The accompanying drawings, which areincorporated in and constitute a part of this specification, illustrateembodiments of the invention and, together with the description, serveto explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof, directed to one of ordinary skill in the art is setforth in the specification, which makes reference to the appendedfigures, in which:

FIG. 1 is a perspective view of a conventional wind turbine;

FIG. 2 is a perspective view of an embodiment of a wind turbine blade inaccordance with aspects of the invention;

FIG. 3 is a cross-sectional view of an exemplary wind turbine blade inaccordance with aspects of the invention;

FIG. 4 is an end view of an embodiment of a seal member;

FIG. 5 is a side cut-away view of a leading edge bond lineconfiguration;

FIG. 6 is a view of the leading edge bond line configuration of FIG. 5with a seal member in accordance with aspects of the invention;

FIG. 7 is a side cut-away view of a seal member embodiment at theleading edge of a wind turbine blade;

FIG. 8 is a side cut-away view of an alternate embodiment of a sealmember at the leading edge of a wind turbine blade;

FIG. 9 is a side cut-away view of still another embodiment of a sealmember at the leading edge of a wind turbine blade;

FIG. 10 is a side cut-away view of a further embodiment of a seal memberat the leading unassembled edge of a wind turbine blade;

FIG. 11 is an assembled view of the embodiment of FIG. 10;

FIG. 12 is a side cut-away view of a bond line configuration at thetrailing edge of a wind turbine blade;

FIG. 13 is a side cut-away view of a bond line configuration at thetrailing edge with a seal member in accordance with aspects of theinvention; and,

FIG. 14 is a side cut-away view of an alternate seal memberconfiguration at the trailing edge bond line.

DETAILED DESCRIPTION OF THE INVENTION

Reference now will be made in detail to embodiments of the invention,one or more examples of which are illustrated in the drawings. Eachexample is provided by way of explanation of the invention, notlimitation of the invention. In fact, it will be apparent to thoseskilled in the art that various modifications and variations can be madein the present invention without departing from the scope or spirit ofthe invention. For instance, features illustrated or described as partof one embodiment can be used with another embodiment to yield a stillfurther embodiment. Thus, it is intended that the present inventioninclude such modifications and variations as come within the scope ofthe appended claims and their equivalents.

FIG. 1 illustrates a wind turbine 10 of conventional construction. Thewind turbine 10 includes a tower 12 with a nacelle 14 mounted thereon. Aplurality of turbine blades 16 are mounted to a rotor hub 18, which isin turn connected to a main flange that turns a main rotor shaft. Thewind turbine power generation and control components are housed withinthe nacelle 14. The view of FIG. 1 is provided for illustrative purposesonly to place the present invention in an exemplary field of use. Itshould be appreciated that the invention is not limited to anyparticular type of wind turbine configuration.

FIG. 2 is a more detailed view of a wind turbine blade 16. The blade 16includes an upper shell member 20 and a lower shell member 22. The uppershell member 20 may be configured as the suction side surface of theblade 16, while the lower shell member 20 may be configured as thepressure side surface of the blade. The blade 16 includes a leading edge24 and a trailing edge 26, as well as a root portion 28, and a tipportion 30. As is well known in the art, the upper shell member 20, andlower shell member 22 are joined together at a bond lines 36 along theleading edge 24 and a bond line 37 at the trailing edge 26. In formationof these bond lines 36, 37, a bond paste 34 (FIG. 5) in flowable viscousform is applied between the mating laminate surfaces of the upper shellmember 20 and lower shell member 22 along the length of the bond lines36, 37. It should be appreciated that the term “bond paste” is usedherein in a generic sense to encompass any type of adhesive or bondingmaterial that is applied in an initially flowable state. The particulartype of bond paste 34 is not particularly relevant to the presentinvention, and any suitable type of epoxy, compound, or other material34 may be used in this regard.

The bond paste 34 is typically applied in a sufficient quantity andpattern so as to establish a designed bond line width 38 at the leadingedge 24 and bond line width 37 at the trailing edge 26 that ensures aminimum bonded surface area between the components along the length ofthe respective bond lines 36, 37. For example, referring to FIG. 5, theleading edge 24 of a turbine blade 26 is depicted. Bond paste 34 isapplied between opposite mating laminate surfaces of the upper shellmember 20 and lower shell member 22 so as to define a bond having adesigned bond width 38 and bond thickness 40. The design criteria forthe bond width 38 and thickness 40 may vary between different types ofblades based on any combination of design factors, as is well understoodby those skilled in the art. For example, referring to FIG. 3, differentbond line widths 37 are depicted at the trailing edge 26 of the blade16.

Referring again to FIG. 5, a particular problem associated with theconventional system and method for application of the bond paste 34 isthat excess bond paste is squeezed out from between the mating surfacesof the upper shell member 20 and lower shell member 22 into the internalcavity 25 (FIG. 3) and eventually cures as a hardened mass 35 that addssignificant weight to the blade 16. The excess mass bond paste 35 doesnot add any degree of structural integrity or other useful purpose tothe blade 16. In the assembly process, a portion of the excess bondpaste 34 may also be squeezed out of the seal gap 46. However, thisexcess material is easily removed along the length of the leading 24 ortrailing edges 36 before it cures.

In order to prevent the situation depicted in FIG. 5, a seal member 32is disposed between the upper shell member 20 and lower shell member 22along the bond lines 36. Various examples of a seal member 32 aredepicted in FIGS. 4, and 6 through 12, and will be discussed in moredetail below. In general, the seal member 32 has a shape andconfiguration such that excess flowable bond paste 34 is prevented frommigrating past the seal member 32 and into the internal cavity 25 uponmating the upper and lower shell members 20, 22 in assembly of the blade16, as depicted in FIG. 6. In essence, the seal member 32 acts as a damto the flowable bond paste 34 and, thus, forces any excess bond paste 34to migrate out from between the shell members 20, 22 through the sealgap 46, wherein the excess material is easily removed.

Desirably, the seal member 32 is provided along each of the leading edge24 and trailing edge 36. However, it is also within the scope and spiritof the invention to include the seal member 32 along only one of thebond lines 36 at the leading edge 24 or trailing edge 26.

The seal member 32 may be formed from any type of suitable material orcombinations of materials. The seal member 32 may be permeable to airyet impermeable to migration of the flowable bond paste 34. In thismanner, any air that is forced out from between the mating surfaces ofthe upper 20 and lower 22 shell members is able to escape through theseal member 32 while the flowable bond paste 34 is forced out throughthe seal gap 46.

A particular embodiment of a seal member 32 is depicted in FIG. 4wherein the seal member 32 includes a dam member 44 attached to each ofthe upper and lower shell members 20, 22. Referring to FIG. 3, the dammembers 44 would be located at the designed bond line width 38. In theembodiment depicted in FIG. 4, each of the dam members 44 is abrush-type seal wherein a plurality of relatively tightly spacedbristles extend along the longitudinal length of the respective dammembers 44. The bristles allow air to pass through the respective dammembers 44 while preventing migration of the bond paste 34 through themembers. The brush seals may overlap, as depicted in FIG. 4, intermesh,or otherwise engage in any other fashion.

It should be appreciated that a single dam member 44 in the form of abrush seal may also be utilized wherein the brush seal has aconfiguration so as to extend from one of the shell members 20, 22 tothe opposite shell member 22, 20.

FIG. 7 illustrates an alternative embodiment of a seal member 32 whereina plurality of dam members 44 are provided and intermesh with eachother. For example, the dam member 44 attached to the laminate portionof the lower shell member 22 intermeshes into the dam member 44 attachedto the laminate portion of the upper shell member 20. In this particularembodiment 20, the dam members 44 may be brush seals wherein thebristles are able to penetrate into the bristles of the opposite brushseal. In an alternative embodiment, the dam members 44 may be relativelysolid members, wherein one of the dam members 44 defines a slot or othertype of receiving channel for receipt of the opposite dam member 44.

FIG. 8 illustrates yet another embodiment of a seal member 32 wherein adam member 44 on the laminate portion of each of the upper and lowershell members 20, 22 extend towards each other and overlap. The dammembers 44 may contact each other at the overlapping portion, or may bespaced from each other. With this particular embodiment, the dam members44 may be more rigid or solid members that are attached or otherwisedirectly and integrally formed in the respective shell members 20, 22.

FIG. 9 illustrates yet another alternative embodiment of a seal member32 wherein a plurality of spaced apart dam members 44 are provided. Thedam members 44 define a “tortuous” path for flowable bond paste 34. Forexample, referring to FIG. 9, it should be readily appreciated that anyflowable bond paste 34 would need to move through a serpentine pathbefore escaping into the internal cavity of the blade. The term“tortuous” is used herein to describe any path having multiple changesof direction so as to inhibit flow of the bond paste 34 completelythrough the dam members 44.

FIGS. 10 and 11 depict an embodiment wherein the dam member 44 isattached to the upper shell member 20, for example to the slantedlaminate face 21, at a location and orientation so as to be engaged by aleading end 23 of the lower shell member 22 when the components areassembled together, as depicted by the arrow in FIG. 10. The dam member44 may be a resilient brush seal. FIG. 11 shows the lower shell member22 moved into its assembled position relative to the upper shell member20. The dam member is engaged (and may be deflected) by the end 23 ofthe lower shell member 22 so as to essentially seal off the gap betweenthe components. Desirably, the dam member 44 is resilient and remainsbiased against the end 23 of the lower shell member 22. The flowablebond paste 34 is injected between the shell members 20, 22 to providethe desired seal thickness and width. The embodiment of FIGS. 10 and 11may be desired for its simplicity and ease of assembly of the shellmembers 20, 22.

FIG. 12 depicts a bond between the upper and lower shell members 20, 22at the trailing edge 26 of a blade. Different bond line widths 39 aredepicted in the figure. Excess bond paste 35 extends beyond either ofthe bond line width dimensions 39 and is problematic for the reasonsdiscussed above.

FIG. 13 illustrates a seal member 32 between the upper and lower shellmembers 20, 22 at the trailing edge in the form of a single dam member44. As discussed above, this dam member 44 may be a brush seal, a solidand rigid material, or any other suitable type of dam material. Thesingle dam member 44 may extend from either of the shell members 20, 22towards the opposite shell member. As can be seen in FIG. 11, the dammember 44 is disposed at the designed dimension of the bond line width39 and prevents the formation of excess bond material in the internalcavity 25.

FIG. 14 illustrates the seal member 32 at the greater of the bond linewidths 38. In this embodiment, the seal 32 is defined by multiple dammembers 44, with at least one dam member 44 extending from each of theupper 20 and lower 22 shell members.

It should be appreciated that any of the embodiments discussed abovewith respect to FIGS. 7 through 11 may be utilized at the bond line 37along the trailing edge bond 26 of FIGS. 13 and 14.

Because the dam member 44 defines a barrier to flow of the bond paste 34into the internal cavity 25 of the blade 16, the present invention mayprovide the additional benefit that the viscosity of the bond paste 34may be increased or otherwise modified to ensure a more completeapplication and elimination of air pockets or voids between the shellmembers along the bond line without the concern that a more viscouspaste would more readily migrate into the cavity 25.

The present invention also encompasses any configuration of a windturbine 10 (FIG. 1) wherein at least one of the blades 16 is configuredwith the unique advantages of the invention as discussed above.

While the present subject matter has been described in detail withrespect to specific exemplary embodiments and methods thereof, it willbe appreciated that those skilled in the art, upon attaining anunderstanding of the foregoing, may readily produce alterations to,variations of, and equivalents to such embodiments. Accordingly, thescope of the present disclosure is by way of example rather than by wayof limitation, and the subject disclosure does not preclude inclusion ofsuch modifications, variations and/or additions to the present subjectmatter as would be readily apparent to one of ordinary skill in the art.

1. A wind turbine blade, said blade comprising: an upper shell memberand a lower shell member defining an internal cavity therebetween; saidupper and lower shell members joined with a bond paste along bond linesat a leading edge and a trailing edge of said blade; a seal memberdisposed between said upper and lower shell members at a designed widthof said bond line along at least one of said trailing or leading edges;said seal member having a configuration such that excess flowable bondpaste is prevented from migrating past said seal member and into saidinternal cavity upon mating said upper and lower shell members inassembly of said blade; and said seal member comprising a dam on each ofsaid lower and upper shell members, said dams overlapping in a matedconfiguration of said upper and lower shell members.
 2. The wind turbineblade as in claim 1, comprising said seal member along each of saidleading and trailing edges.
 3. The wind turbine blade as in claim 1,wherein said dams are air permeable.
 4. The wind turbine blade as inclaim 3, wherein said dams comprise a brush seal attached to each ofsaid upper and lower shell members and extending towards the oppositerespective said shell member.
 5. The wind turbine blade as in claim 1,wherein said dams are intermeshing.
 6. The wind turbine blade as inclaim 1, wherein said seal member comprises a dam on each of said lowerand upper shell members, said dams overlapping.
 7. The wind turbineblade as in claim 1, wherein said seal member comprises a plurality ofsaid dams interlaced to define a tortuous path for flowable bond paste.8. The wind turbine blade as in claim 1, further comprising a seal gapat said leading or trail edge opposite from said seal member, said sealgap providing an opening through which excess flowable bond pastemigrates out from said bond line during assembly of said blade.
 9. Awind turbine, said wind turbine comprising a plurality of turbineblades, at least one of said turbine blades comprising: an upper shellmember and a lower shell member defining an internal cavitytherebetween; said upper and lower shell members joined with a bondpaste along bond lines at a leading edge and a trailing edge of saidblade; a seal member disposed between said upper and lower shell membersat a designed width of said bond line along at least one of saidtrailing or leading edges; said seal member having a configuration suchthat excess flowable bond paste is prevented from migrating past saidseal member and into said internal cavity upon mating said upper andlower shell members in assembly of said blade; and said seal membercomprising a dam on each of said lower and upper shell members, saiddams overlapping in a mated configuration of said upper and lower shellmembers.
 10. The wind turbine as in claim 9, comprising said seal memberalong each of said leading and trailing edges of said turbine blade. 11.The wind turbine as in claim 19, wherein said dams are air permeable.12. The wind turbine as in claim 11, wherein said dams comprise a brushseal attached to each of said upper and lower shell members andextending towards the opposite respective said shell member.
 13. Thewind turbine as in claim 9, wherein said dams are intermeshing.
 14. Thewind turbine as in claim 9, wherein said seal member comprises aplurality of said dams interlaced to define a tortuous path for flowablebond paste.
 15. The wind turbine as in claim 9, further comprising aseal gap at said leading or trail edge opposite from said seal member,said seal gap providing an opening through which excess flowable bondpaste migrates out from said bond line during assembly of said blade.